Recently, information terminal apparatuses, such as a light-weight palm top type information terminal, a wrist watch type information terminal, a wrist watch type computer, and a small electronic cameras have been proposed. For example, Japanese Patent Laid-Open Publication No. 2002-125039 describes a wrist watch type information terminal.
FIG. 14 shows an appearance of the wrist watch type information terminal described in the related art. As shown in FIG. 14, the wrist watch type information terminal is composed of a main body 101 and a wrist band 102 that is secured to both end portions of the main body 101. Disposed at a nearly center portion on an upper surface of the main body 101 is a display portion 103 that displays various types of information. Disposed at a lower portion on the upper surface of the main body 101 are buttons 104a, 104b, and 104c with which the wrist watch type information terminal is operated. Disposed at a lower portion of the main body 101 is an extension portion 105 that has a plurality of buttons 106 with which information is input.
However, as shown in FIG. 14, since the wrist watch type information terminal is small, the input buttons are small. Thus, it is troublesome to operate the buttons and the user tends to operate the wrist watch type information terminal mistakenly. When the sizes of the buttons are increased, the size of the wrist watch type information terminal becomes large and the design thereof deteriorates. In addition, when the buttons are exposed to the outside of the wrist watch type information terminal, the buttons may be damaged or the design of the terminal may deteriorate.
In a palm top type PDA (Personal Digital Assistance) and so forth, an input operation is performed by tapping a button that appears on a screen with a pen type input device. However, since the pen type input device is separated from the main body, the pen type input device tends to be lost. In addition, when an input operation is performed, both the main body and the pen type input device need to be taken out. Thus, the input operation becomes complicated. In addition, when information is input to the portable information terminal with the pen type input device, it needs to have an information input area on the front surface. Thus, the size of the portable information terminal becomes large and the design thereof deteriorates.
Therefore, an object of the present invention is to provide an input apparatus, an information terminal apparatus, and a mode switching method that allow an input operation to be stably and easily performed without the tradeoffs of an increase of the size and a deterioration of the design.